[SSSD] Re: [PATCH ding-libs] Extend API to const key for clients that don't need to modify their keys

[Michal Židek]

ACK to the code from Philip. I amended the commit
message to meet our style.

I would like to push this together with at least some
sanity tests. See the second patch. I am looking for
someone from SSSD developers to review the tests.

Michal

PS: Btw. Philip, I am interested for what project are you
using ding-libs.

On 09/30/2016 11:55 PM, Philip Prindeville wrote:

From: Philip Prindeville <phil...@fedoraproject.org>

Add c_str as a "const char *" to the hash_key_t.

Redux per comments from Michal Zidek.
---
  dhash/dhash.c               | 29 +++++++++++++++++++++--------
  dhash/dhash.h               |  4 +++-
  dhash/examples/dhash_test.c |  3 +++
  3 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/dhash/dhash.c b/dhash/dhash.c
index 45ee0cf..98439e8 100644
--- a/dhash/dhash.c
+++ b/dhash/dhash.c
@@ -176,7 +176,7 @@ static void sys_free_wrapper(void *ptr, void *pvt)
  static address_t convert_key(hash_key_t *key)
  {
      address_t h;
-    unsigned char *k;
+    const unsigned char *k;

      switch(key->type) {
      case HASH_KEY_ULONG:
@@ -184,7 +184,12 @@ static address_t convert_key(hash_key_t *key)
          break;
      case HASH_KEY_STRING:
          /* Convert string to integer */
-        for (h = 0, k = (unsigned char *) key->str; *k; k++)
+        for (h = 0, k = (const unsigned char *) key->str; *k; k++)
+            h = h * PRIME_1 ^ (*k - ' ');
+        break;
+    case HASH_KEY_CONST_STRING:
+        /* Convert string to integer */
+        for (h = 0, k = (const unsigned char *) key->c_str; *k; k++)
              h = h * PRIME_1 ^ (*k - ' ');
          break;
      default:
@@ -212,6 +217,7 @@ static bool is_valid_key_type(hash_key_enum key_type)
      switch(key_type) {
      case HASH_KEY_ULONG:
      case HASH_KEY_STRING:
+    case HASH_KEY_CONST_STRING:
          return true;
      default:
          return false;
@@ -244,6 +250,8 @@ static bool key_equal(hash_key_t *a, hash_key_t *b)
          return (a->ul == b->ul);
      case HASH_KEY_STRING:
          return (strcmp(a->str, b->str) == 0);
+    case HASH_KEY_CONST_STRING:
+        return (strcmp(a->c_str, b->c_str) == 0);
      }
      return false;
  }
@@ -670,8 +678,11 @@ int hash_destroy(hash_table_t *table)
                          while (p != NULL) {
                              q = p->next;
                              hdelete_callback(table, HASH_TABLE_DESTROY, 
&p->entry);
-                            if (p->entry.key.type == HASH_KEY_STRING) {
-                                hfree(table, (char *)p->entry.key.str);
+                            if (p->entry.key.type == HASH_KEY_STRING
+                                    || p->entry.key.type == 
HASH_KEY_CONST_STRING) {
+                                /* Internally we do not use constant memory 
for keys
+                                 * in hash table elements. */
+                                hfree(table, p->entry.key.str);
                              }
                              hfree(table, (char *)p);
                              p = q;
@@ -972,13 +983,14 @@ int hash_enter(hash_table_t *table, hash_key_t *key, 
hash_value_t *value)
              element->entry.key.ul = key->ul;
              break;
          case HASH_KEY_STRING:
-            len = strlen(key->str)+1;
+        case HASH_KEY_CONST_STRING:
+            len = strlen(key->c_str) + 1;
              element->entry.key.str = halloc(table, len);
              if (element->entry.key.str == NULL) {
                  hfree(table, element);
                  return HASH_ERROR_NO_MEMORY;
              }
-            memcpy((void *)element->entry.key.str, key->str, len);
+            memcpy(element->entry.key.str, key->str, len);
              break;
          }

@@ -1070,8 +1082,9 @@ int hash_delete(hash_table_t *table, hash_key_t *key)
                  return error;
              }
          }
-        if (element->entry.key.type == HASH_KEY_STRING) {
-            hfree(table, (char *)element->entry.key.str);
+        if (element->entry.key.type == HASH_KEY_STRING
+                || element->entry.key.type == HASH_KEY_CONST_STRING) {
+            hfree(table, element->entry.key.str);
          }
          hfree(table, element);
          return HASH_SUCCESS;
diff --git a/dhash/dhash.h b/dhash/dhash.h
index baa0d6a..c36ab79 100644
--- a/dhash/dhash.h
+++ b/dhash/dhash.h
@@ -112,7 +112,8 @@ typedef struct hash_table_str hash_table_t;

  typedef enum {
      HASH_KEY_STRING,
-    HASH_KEY_ULONG
+    HASH_KEY_ULONG,
+    HASH_KEY_CONST_STRING
  } hash_key_enum;

  typedef enum
@@ -137,6 +138,7 @@ typedef struct hash_key_t {
      hash_key_enum type;
      union {
          char *str;
+        const char *c_str;
          unsigned long ul;
      };
  } hash_key_t;
diff --git a/dhash/examples/dhash_test.c b/dhash/examples/dhash_test.c
index 303e9f8..7613e23 100644
--- a/dhash/examples/dhash_test.c
+++ b/dhash/examples/dhash_test.c
@@ -64,6 +64,9 @@ static char *key_string(hash_key_t *key)
      case HASH_KEY_STRING:
          snprintf(buf, sizeof(buf), "key string = \"%s\"", key->str);
          break;
+    case HASH_KEY_CONST_STRING:
+        snprintf(buf, sizeof(buf), "key string = \"%s\"", key->c_str);
+        break;
      default:
          snprintf(buf, sizeof(buf), "unknown key type = %d", key->type);
          break;

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